Declared compressive strength of masonry units to BS EN 771-1 to 5

Table 4C.6 Declared compressive strength (N/mm²) of masonry units complying with BS EN 771-1 to 5 Masonry unit: Clay masonry units to BS EN 771-1, Calcium silicate masonry units to BS EN 771-2, Aggregate concrete masonry units to BS EN 771-3, Autoclaved aerated concrete masonry units to BS EN 771-4, Manufactured stone masonry units to BS EN 771-5 Condition A (see Diagram 4C.7): Brick Group 1: 6.0, Group 2: 9.0 Block: see Table 4C.7 Calcium silicate - Brick Group 1: 6.0, Group 2: 9.0; Block: see Table 4C.7 Aggregate concrete - Brick: 6.0, Block: 2.9* Autoclaved aerated concrete - Brick: –, Block: 2.9* Manufactured stone - Any unit complying with BS EN 771-5 will be acceptable for conditions A, B and C Condition B (see Diagram 4C.7): Brick Group 1: 9.0, Group 2: 13.0 Block: see Table 4C.7 Calcium silicate - Brick Group 1: 9.0, Group 2: 13.0; Block: see Table 4C.7 Aggregate concrete - Brick: 9.0, Block: 7.3 Autoclaved aerated concrete - Brick: –, Block: 7.3 Condition C (see Diagram 4C.7): Brick Group 1: 18.0, Group 2: 25.0 Block: see Table 4C.7 Calcium silicate - Brick Group 1: 18.0, Group 2: 25.0; Block: see Table 4C.7 Aggregate concrete - Brick: 18.0, Block: 7.3 Autoclaved aerated concrete - Brick: –, Block: 7.3 Notes: 1. This table applies to Group 1 and Group 2 units. 2. For the BS EN 771 series of standards for masonry units the values of declared compressive strengths (N/mm²) mean values. 3. Brick is a masonry unit having work sizes not exceeding 337.5 mm in length or 112.5 mm in height. 4. Block is a masonry unit exceeding either of the limiting work sizes of a brick and with a minimum bed height of 190 mm. For blocks with smaller bed heights, excluding cuts or make up units, the strength requirements are as for brick except for solid external walls where the blocks should have a compressive strength at least equal to that shown for block for an inner leaf of a cavity wall in the same position. 5. Group 1 masonry units have not more than 25% formed voids (20% for frogged bricks). Group 2 masonry units have formed voids greater than 25%, but not more than 55%. 6. Values marked * are dry strengths to BS EN 772-1.